In a principal aspect, this invention relates to an improved overrun control valve which is resettable and adjustable.
Air operated tools such as paint pumps or grinders can malfunction. In such instances the volume of air to the pneumatically operated apparatus or tool may drastically increase. Consequently, the pump or grinder may be destroyed or operate at such an excessive speed that all control of the tool is lost.
Various mechanisms have been proposed to sense the unsafe tool operating condition and to stop the air flow to the tool until the undesirable condition is corrected. One such mechanism is suggested by U.S. Pat. No. 3,618,689 which discloses a structure for an overrun control valve and pressure regulator. This valve device not only controls the pressure of pneumatic fluid to an air tool, but also automatically terminates excessive air flow through the valve to the tool. The disclosure of U.S. Pat. No. 3,618,689 is incorporated herewith by reference.
A recently available valve construction which provides a similar function is known as a flow check valve. This device responds automatically to an inordinate pressure reduction on the downstream side of the valve due to tool failure or air hose rupture, for example. Thus, if an air hose ruptures or is cut or accidentally uncoupled, the sudden pressure reduction on the downstream side of the Flow Check will close the valve automatically causing termination of substantially all of the air flow. Such a valve is disclosed in the drawing of the present application as prior art and is described in greater detail below.
While such prior art valves operate effectively and efficiently, the need exists for an improved flow check valve which is both adjustable and resettable. The present invention provides a compact, inexpensive and efficient construction providing such features.